Dental device



Patented Mar. 18, 1930 UNITED STATES PATENT QFFICE GEORGE M. HOLLENBACK, DE LOS ANGELES, CALIFORNIA DENTAL DEVICE Application filed February 12, 1927. Serial No. 167,826.

This invention relates to dental devices, and has for an object the provision of a device wh'ich automatically and properly treats investments in such a manner as to not destroy the integrity of the investment.

Further objects include the provision of a device of the character stated which is simple of construction, positive in operation and generally superior.

With the above and other objects in view, the invention consists in the novel and useful provision, formation, construction, association and relative arrangement of parts, members and features, all as shown in a certain embodiment in the accompanying drawing, described generally and more particularly pointed out in the claims.

In the drawing:

Figure 1 is a side elevation tion of the improved device;

Figure 2 is a view similar to Figure 1 and showing a second position of certain elements of the invention;

Figure 3 is a front elevation of the device; Figure 4 is a rear elevation of the device; Figure 5 is a fragmentary perspective view an element of the device; and,

Figure 6 is a plan view of the flask carrier. Corresponding parts in all the figures are designated by the same reference characters.

Before describing the invention in detail I wish to emphasize the importance of providing investments which will correctly mold an article such as inlays. The usual method partly in secis to provide wax which has a contour corresponding with the contour of the inlay to be made. This wax is impaled upon some sharp object like a needle and then investment material is placed around both the needle and the wax. This investment material is of course placed in a flask. After the investment material has properly formed it is imperative that the wax be correctly removed therefrom and manufacturing dentists have resorted to numerous ways of accomplishing this, but a neat job is not always obtainable, one reason being that the investment material is usually gypsum which arrives at the dental. laboratory in a powdered form, that is to say, the gypsum has been calcined to remove the water therefrom. The manufacturing dentist restores this water to the gypsum so that the investment will maintain its form. The gypsum if heated to about 268 degrees F. will drive off all its water content and again assume the powdered form, and therefore the dentists problem in casting is to provide an investment which will not fail because of employing too great heat or pressure, or both. There is a drawback, in that the volatilizing temperature of the wax is always greatly in excess of the disintegrating temperature of the investment. Now, in order to remove this wax it is customary to heat the investment and try to melt the wax therefrom, but the flash point of the wax being in excess of the disintegrating temperature of the investment, the result will be that either the investment is ruined or part of the wax remains within the investment. If molten metal is then poured in the investment and upon the wax which remains therein, the metal which has been heated greatly in excess of the flash point of the wax, will instantly cause the wax to become volatilized, producing excessive gas pressure within the investment; in other words, trapping the gas within the mold which will result in an imperfect and illfitting casting.

After the wax has been properly removed from the investment the next step is to remove the excess of moisture from the investment or mold and to do this in such a manner that the plaster bond of the investment, which constitutes the mold, is not subjected to a sufiicient degree of heat for a sufficient length of time to destroy its integrity.

Referring with particularity to the drawing, the improved device for removing excessive moisture from the mold is designated as an entirety by A. Said device includes a heating element a, means 5 for holding investments c in a position to be acted upon by the heating means, and means d adapted to remove the investment from the influence of said means a.

I provide a base 1 upon which is mounted a pair of spaced standards 2 and 3. Associated with the standards and extending above rier or receptacle 8 and a central stem 9, to

which stem is joined the said member 7 as shown at 10. A bracket 11 is joined to the base 1 at 12 and said bracket supports the timing device cl. This timing device in the present instance comprises a clock 13 having a spindle 14 extending outwardly from the rear wall of the clock and associated with the mechanism that controls movement of the minute-hand. This spindle is provided with a U-shaped member 15 constituting a release member; Projecting substantially at right angles to the stem 9 is a pin 16 which is adapted to be received within the U-shaped member 15 when the U-shap'ed member is in a definite position.

The furnace at comprises an annular coil 7 of resistance wire 17 suitably wound upon an annular core 18 and when the flask carrier 8 is in its elevated position such flask carrier is received in part within the annular opening 19 of said furnace. At 20 I have shown one form of thermostat, which thermostat may comprise two metals adapted to make contact under influence of heat, and of 7 course this thermostat may be regulated inv accordance with the temperature desired before it makes contact. The thermostat would be in circuit with the coil 17,,and binding posts 21 are provided whereby the furnace may be connected to a suitable source of electriccurrent.

The operation of the device just described is as follows: The flasks containing the in- .vestments are placed upon the flask carrier or tray 8, and the stem 9 is raised so that said flasks are received within the annular space 19 of the furnace. The pin 16 will of course be raised and said pin will be received within the U-shaped member 15 constituting the release when the said spindle is turned to position the release as shown in Fig. 5. The minute hand is set for the desired period of time, and after such duration of time the spindle will turn so as to release the pin 16 from a the member 15 and allow the tray 8 with the flask to drop, as shown in Figure 2. When this occurs a tipping pin 22 mounted upon the base 1 will pass through an opening in the I carrier 8 and strike the flask to release said flask or flasks from said carrier 8 and deposit the flask in a basket or tray 23. This tray or basket is preferably lined with some heat-resistant material such as asbestos, and the said flasks are allowed to cool in said tray.

In place of the spindle d being associated with the minute hand, the timing device may take the form of an alarm clock and the spindle would be associated with the mechanism that ordinarily sets off the alarm. In this manner the timing might be for an hour or two or for a few minutes, and the spindle would not be rotated by the minute hand but only be rotated at the time set. The thermostat 20 would regulate the heat of the furnace so that a given temperature-would be maintained, although it is evident the electrical furnaces give out a fairly constant heat when the source of current supply is fairly constant. When this'is the case a mere timing of the device would be all that would be necessary. v

The device is ly efficient manner.

It is obvious that various changes. and

modifications may be made in practicing the invention, in departure from the particular.

a heating oven having a chamber open at its lower end and formed to receive a. flask,a

flask carrier movable vertically into and out of the oven, means for supporting said flask within the heating oven for a'predetermined length of time and for releasing'thecarrier at the end of sa-id time, and means for enabling said carrier'to drop a suflicient distance to withdraw the flask completely from the heating oven when the carrier is released.

2. In a'device of the character as described,

a flask carrier including a pin, a timing device including a spindle formed vWith a U-shaped ekceeding'ly simple of con-. struction, yet performs its function in a highend to receive said pinto support said carrier in a predetermined position until the spindle is rotated by the timing device so that said U-shaped end is inverted, and means formounting said carrier to withdraw the flask from said position when said pin falls from said inverted U-shaped spindle end. 3. In a deviceof the character as described, a heating element formedvto receive a flask, a flask carrier, means for supporting said flask within the heating element andfor releasing the carrier, means for enabling said,

carrier to withdraw the flask completely from the heating element when the carrier is 'released and means for ejecting the flask from said carrier when the latter is Withdrawn from said heating element.

4. In a device of the character as described, a heating element formed to receive a flask, a flask carrier, means for supporting said flask within the heating element and for releasing the carrier,'1neans for enabling said carrier towith'draw the flask completely from the heating element when the carrier is released and a tipping pin arranged to engage and tip the flask so that it will fall out of the carrier when the carrier is moved to Withdraw the flask from said heating element.

In testimony whereof, I have signed my name to this specification.

GEORGE M. HOLLENBAOK. 

